(1) Field of the Invention
The present invention relates to an excavating vehicle comprising a swivel base provided with an excavating apparatus, a hydraulic actuator for rotating the swivel base, and a valve for operating the hydraulic actuator.
The excavating apparatus mounted on an excavating vehicle excavates the ground into a ditch or a hole and carries excavated sand to a loading stand of a truck or to a sand discharging place and returns to the excavating place.
Namely, the swivel base where the excavating apparatus is mounted must be driven and stopped correctly and repeatedly at positions making a predetermined angle relative to the vehicle.
(2) Prior Art
According to the prior art, a swivel base with which an excavating apparatus is provided has been driven or stopped by operating a control valve manually in good timing. Therefore, such a control apparatus is disadvantageous in that shocks are given to the excavating vehicle and the hydraulic circuits thereof and discomfort is given to an operator of the vehicle as a result of a big moment of inertia of the swivel base and other apparatuses mounted thereon generated by stops of the swivel base. Such a manual control may close the valve quickly, but cannot operate the valve precisely stop the swivel base at a desired position. In addition to the above described disadvantage, the prior art is also disadvantageous in that a good mechanical skill is required of the operator in stopping the swivel base at a predetermined angle relative to the excavating vehicle and that nerve strain is given to the operator as a result of his repeated operations of stopping the swivel base in good timing.